Koi Pond Building
Bespoke Koi Pond Design and Construction
We design and build koi ponds around the fish you keep, the garden you have and the way you want to enjoy both. Our work ranges from compact garden ponds to complete rebuilds with viewing windows, patios, planting and space to sit beside the water.
We keep koi ourselves and use equipment on our own ponds that we also install for customers. That practical experience shapes the conversations we have about filtration, access for cleaning and the time you want to spend looking after your pond.
A successful koi pond needs more than an attractive finish. We plan the structure, depth, circulation and filtration together, so the equipment and the pond work as a system and remain accessible for everyday care.
Koi Pond Building Across the South East
We design and construct koi ponds for private gardens and estates across Kent, London, Essex, Surrey, Sussex and the wider South East. We consider the setting from the start, whether the pond occupies a small town garden or forms part of a larger landscaped property.
Our koi pond building service forms part of our wider pond building work. It focuses on the particular demands of keeping koi, including fish load, water volume and ongoing maintenance.
Explore our koi pond showcase to see completed builds, customer reviews and the choices behind individual projects. Our pond projects also cover restoration and other specialist work.
Designing Koi Ponds That Work Long Term
Koi can grow large and produce substantial waste. We therefore consider the fish you have now and your plans for the pond when discussing its volume, depth and filtration. Stable water conditions depend on the design and the care the pond receives after construction.
Shape, wall construction, bottom drains and circulation need to be planned together. We look at how waste will move towards the filtration, where water might circulate poorly and how the depth will affect the pond through the seasons.
The view matters too. We consider what you will see from the house or seating area, how paving and planting meet the pond, and whether a glass window would make the fish easier to enjoy. Many of our builds use a seamless fibreglass lining for a durable surface that suits the shape and detailing of the pond.
Eltham: a new pond for an experienced koi keeper
Denis wanted to replace his ageing pond while keeping the hands on side of koi keeping. We rebuilt it with a large viewing window and housed the equipment in a purpose built shed. A Nexus 320 serves the main pond, with a separate bead filter on the skimmer line. His preference for routine involvement helped shape that choice.
“The new pond is modern, looks incredible, and features a great filtration system housed inside a purpose built shed.”
Denis Edwards, customer review excerpt
The photographs below show the pond before and after the work. See Denis’s koi pond renovation in Eltham and read his full review.
Filtration, Water Quality and Koi Health
Choosing filtration starts with pond volume, fish stock, feeding and how you want to maintain the pond. We also consider space, pipe runs, pump flow, waste disposal and access to the equipment. A filter that is awkward to reach or clean can make routine care unnecessarily difficult.
Mechanical filtration removes solid waste. Biological filtration supports the bacteria that process dissolved fish waste. Both need to be considered alongside circulation and aeration, rather than choosing a filter in isolation.
A drum filter can automate part of the cleaning. Our All Hallows and Wateringbury builds used Burtons BD300 Combi filters, while Denis’s Eltham pond uses a different arrangement to suit his preference for hands on care. There is no single model that is right for every pond.
We arrange pipework, valves and equipment so checks and servicing can be carried out comfortably. Clear water alone does not confirm that water conditions are suitable for koi: water testing, equipment checks and ongoing care still matter, including with an automated filter.
We also offer ongoing pond care services, including maintenance, health checks, equipment servicing and seasonal support.
Koi Ponds as Part of Complete Garden Transformations
Many koi pond projects form part of a wider garden layout rather than existing in isolation. In these situations, the pond is designed alongside paving, planting, seating areas, and garden structures. As a result, the entire space functions as a cohesive outdoor environment rather than a collection of separate features.
We regularly carry out full garden transformations alongside koi pond construction. This includes all associated hard landscaping and soft landscaping. Projects may involve new patios, pathways, retaining walls, raised planters, steps, pergolas, screening, and planting schemes. Each element is planned to complement the pond and create a balanced, usable garden.
Each project is approached with careful consideration of how the space will be used day to day. We plan sightlines from seating areas, access routes, changes in level, and material choices together. This approach helps the pond feel naturally integrated into the garden rather than added on afterwards.
We often incorporate raised pond walls, carefully detailed coping, and glass viewing windows to improve both usability and appearance. These features allow koi to be enjoyed from within the garden. They also help the pond sit comfortably within its surroundings and remain practical to maintain.
Examples of this integrated approach can be seen throughout our koi pond showcase, where completed projects are shown as part of fully finished outdoor spaces rather than just the pond itself.
Our Approach to Koi Pond Construction
Every koi pond build follows a clear, methodical process tailored to the individual site and garden layout. Although no two projects are ever identical, the same core principles apply throughout to ensure each build is carried out carefully and consistently from start to finish.
We begin by discussing how the pond will be used and how many koi it needs to support. We also consider how it will fit into the wider garden. At an early stage, we assess practical factors such as access, ground conditions, levels, and surrounding features. From there, we design the pond structure, filtration layout, pipework, and equipment specification to suit the site rather than forcing a standard solution.
From Design Through to Completion
Construction typically includes excavation, structural preparation, professional lining, and the installation of filtration, circulation, and aeration systems. Each stage follows a controlled sequence. As a result, accuracy, durability, and long term reliability are maintained throughout the build.
We give close attention not only to the pond itself, but also to associated elements such as filter areas, pipe runs, and access points. We arrange these carefully so the system remains practical to use and easy to maintain.
Once construction is complete, we fill, test, and balance the system carefully. We then provide clear guidance on stocking levels, feeding, seasonal care, and ongoing maintenance. This helps the pond start its life in the best possible condition and continue to perform as intended over time.
From a Sketch to a Koi Pond and Garden in Gravesend
Gavin came to us with a drawing of the pond he wanted. The completed project brought together a koi pond with two viewing windows, a pergola, Indian sandstone patios, raised planters and screening. We planned the pond and its surrounding seating areas as one garden project.
“Matt, Harvey and the team took a drawing I did on the back of an envelope and turned a wasteland at the end of our garden into a 7000l pond with pergola, patio and screening.”
Gavin Larkins, customer review excerpt
See Gavin’s pond and garden renovation in Gravesend for the photographs, project details and his full review. The photographs below show the finished pond and the garden during the work.
Alongside new builds, we take on renovations involving existing pond structures, filtration upgrades and complete redevelopment. Our wider pond projects show more of this specialist work.
Is a Koi Pond Right for Your Garden?
A koi pond is a long term investment, both financially and practically. Getting the design right from the outset makes a real difference to ease of maintenance, fish health, and how much enjoyment the pond provides over time.
If you are still deciding whether a koi pond suits your garden, read our guide to the benefits of having a koi pond before planning the build.
Whether you are considering a koi pond as part of a wider garden layout or as a standalone feature, taking time to plan properly is essential. Looking at real, completed projects can be a helpful starting point. Below, you can view examples of our completed pond builds, or explore our koi pond showcase for a more detailed breakdown of selected koi pond projects shown in full context.
If you would like clear, practical advice, we are always happy to help. We can talk through layout, depth, filtration, and finishes, and advise on what will work best for your garden and long term maintenance expectations. For a wider range of specialist work, including restorations and unusual projects, you can also explore our pond projects page.
If you would like to discuss a project, please get in touch. We work with clients across Kent, London, Essex, Surrey, Sussex, and the wider South East, and will come back to you with the next steps once we understand a little more about your space and requirements.
Tell us about the koi pond you have in mind
You do not need a finished design before getting in touch. A few details about your garden and what you want from the pond will help us understand the project.
- Your postcode and whether you are planning a new pond or changing an existing one.
- Approximate length, width and depth, if you have them. A rough idea is fine at this stage.
- Photos of the proposed pond area and the route through the garden, especially any narrow gates or steps.
- The koi you keep or plan to keep, and the time you want to spend on routine maintenance.
- Features you would like to discuss, such as raised walls, a viewing window or surrounding landscaping, together with your approximate budget.
Use the enquiry form below to share what you know. Access, ground conditions, the pond structure and the filtration layout all need to be considered before a build can be priced accurately.
Contact Us
Please get in touch to discuss your pond needs and we will get back to you as soon as possible.
matt@thatpondguy.co.uk
07368 372129
Koi Pond Building – Frequently Asked Questions
How much does it cost to build a koi pond?
The cost of building a koi pond varies significantly because no two ponds are ever the same. Factors such as size, depth, access, filtration specification, lining method, viewing windows, and surrounding landscaping all influence the final cost.
As a very broad guide, professionally built koi ponds typically range from around £10,000 up to £100,000. Some projects fall outside this range depending on complexity. The most important thing to understand is that koi ponds are highly individual builds, so accurate pricing always depends on the details of the site and the design.
Many of the factors that influence cost can be seen in our completed builds within the koi pond showcase.
Why is there such a big price difference between koi ponds?
The biggest differences usually come down to scale and specification. A compact koi pond with straightforward access and standard finishes will cost far less than a large, raised pond with glass windows, high end filtration, and a full garden renovation around it.
Access also plays a major role. If materials and waste need to be moved by hand rather than machinery, labour time increases quickly. Filtration choice, structural work, and finishes all add to the overall cost as well.
Can you give a rough starting budget?
For a serious koi pond built with correct depth, structure, and filtration, most projects start in the five figure range. From there, costs increase depending on features such as windows, raised walls, premium finishes, or integrated landscaping.
We always prefer to discuss realistic expectations early, so clients can decide what level of build makes sense for their space and priorities.
Do you build koi ponds in my area?
We design and build koi ponds across Kent, London, Essex, Surrey, Sussex, Berkshire, Hampshire, and the wider South East. This includes urban gardens, rural properties, estates, and larger landscaped grounds.
If you are unsure whether we cover your area, a quick message with your location is usually enough for us to confirm.
How long does a koi pond build take?
Timescales vary depending on size, access, weather, and the construction method. Many koi pond builds take place over several stages rather than being completed in one continuous run.
Smaller builds can sometimes be completed in around a week, while larger or more complex projects can take several weeks. We always explain realistic timeframes early so expectations are clear.
Do I need planning permission for a koi pond?
In many cases, koi ponds in private gardens do not require planning permission. However, raised structures, boundary changes, listed buildings, conservation areas, or significant landscaping can alter what is required.
If a project sits in a sensitive location, it is always best to check early so there are no issues later.
How deep should a koi pond be?
Depth depends on the size of the pond, the number of koi, and how the pond will be used. In general, koi ponds need far more depth than standard garden ponds to support stable temperatures and healthy fish.
Rather than working to a fixed number, we design depth based on pond volume, filtration, and long term fish welfare.
Why do koi ponds need specialist design?
Koi grow large, produce a lot of waste, and place greater demands on water quality than most pond fish. That means koi ponds require proper circulation, correctly sized filtration, and thoughtful structural design.
A pond that looks fine on the surface can struggle long term if these factors are not addressed from the start.
What is the best lining for a koi pond?
Fibreglass is a popular choice for koi ponds because it creates a seamless, durable, watertight surface that is easy to maintain and built to last. It also allows for precise finishes and works well with raised ponds and viewing windows.
You can read more about this process on our pond fibreglassing page.
Is fibreglass safe for koi?
Yes, when installed and cured correctly. A properly finished fibreglass surface is smooth, strong, and safe for fish. Correct preparation and curing time are essential, which is why professional installation matters.
Can you include glass viewing windows?
Yes. Glass viewing windows can be incorporated into koi ponds where the structure allows. When designed properly, they create a striking feature and allow koi to be enjoyed from within the garden rather than only from above.
Several examples of ponds with viewing windows can be seen in our koi pond showcase.
Are raised koi ponds better than in ground ponds?
Neither option is automatically better. Raised ponds often offer improved viewing and easier access, while in ground ponds can suit more natural garden layouts.
We choose the approach that best suits the garden, the style you prefer, and how the pond will be used day to day.
What filtration systems do you use?
Filtration is always specified to match pond volume, fish stock, and maintenance expectations. Many modern koi ponds use a combination of mechanical filtration, biological filtration, and aeration.
Drum filters are commonly used because they automate waste removal and reduce manual cleaning, but the overall system design matters more than any single component.
How much maintenance does a koi pond need?
Maintenance depends on design, filtration choice, and stocking levels. A well designed koi pond with correct filtration can be far easier to manage than people expect.
That said, no koi pond is maintenance free. Regular checks and seasonal care are still required. We also offer ongoing pond care services for clients who want professional support.
Do koi ponds lose water?
Some water loss through evaporation is normal, especially in warm weather. However, noticeable daily drops can indicate leaks, pipework issues, or water feature losses.
We design systems carefully to minimise unnecessary water loss and make any issues easier to identify.
How much does it cost to run a koi pond?
Running costs depend on pump efficiency, filtration type, UV use, and whether heating is installed. Efficient equipment selection makes a big difference over time.
We aim to balance performance with sensible running costs rather than oversizing systems unnecessarily.
Can you hide the filtration equipment?
Yes. Filtration can be housed in discreet filter bays, timber filter houses, screened areas, or dedicated plant rooms depending on the site.
We plan this early so access remains practical without the equipment dominating the garden.
Can an existing pond be converted into a koi pond?
In many cases, yes. Existing ponds can often be rebuilt or upgraded to improve depth, structure, and filtration. However, some ponds are better replaced entirely once assessed.
You can read more about full rebuild options on our pond building page.
Can a koi pond be part of a full garden renovation?
Absolutely. Many koi ponds are built as part of complete garden transformations. This can include patios, paths, raised planters, retaining walls, pergolas, screening, and planting schemes.
Designing everything together usually produces a far better finished result. Our wider pond building service covers both koi ponds and surrounding garden works.
What information should I provide before getting in touch?
Helpful information includes your location, a few photos of the garden, any rough dimensions, and notes on what you would like to achieve. Access details are also useful if the site is restricted.
This allows us to give more meaningful advice from the start.
Do you offer support after the build?
Yes. We provide guidance during the early stages while the pond settles and can continue to support clients with servicing, maintenance, and long term care if required.
Support options are available through our pond maintenance services.
Can koi ponds be heated?
Koi ponds can be heated, but heating is not essential for every setup. Whether heating makes sense depends on pond depth, filtration, stocking levels, and how the koi will be fed through the year. We can advise on whether heating would be beneficial based on how the pond will be used long term.
What are the most common mistakes people make with koi ponds?
The most common issues usually come from ponds being built too shallow, under filtered, or without proper circulation. In many cases, problems only appear months or years later once fish grow and waste loads increase. Careful design from the start avoids most long term issues.
Can you work around existing trees or mature gardens?
Yes. Many projects involve working within established gardens or around mature planting. Access, root protection, and layout all need careful planning, but it is often possible to design a koi pond that respects existing features rather than removing them.
Is a koi pond safe for children or pets?
Safety is always considered during design. Raised walls, coping details, planting, and layout can all help manage risk. Where required, additional safety measures can be incorporated without compromising the appearance of the pond.
When is the best time of year to build a koi pond?
Koi ponds can be built throughout much of the year, but weather and ground conditions do affect scheduling. Spring and summer are popular because ponds can be enjoyed straight away, while autumn builds often allow systems to mature before the following season.
Final note
If you would like to see completed builds in context, our koi pond showcase shows selected projects in full detail. For a broader range of specialist work, including renovations and unusual builds, you can also explore our pond projects page.
